The purpose of the seven studies proposed here is to indicate developmental changes in the use of information in the perception of self and others. Information about others includes consensus, distinctiveness, variability of situations, interjudge agreement, emotional adjustment, provocation, effort, ability, intention, and consequences. Children and adolescents will be asked to form impressions about these hypothetical persons. One study deals with developmental changes in the perception of self and other. The use of information and the causal schemes facilitating this use are related to a general Piagetian approach to attribution processes. The use of information will be related to other social and non-social cognitive abilities, such as role-taking and formal operational thinking. The general procedures will include questionnaires measuring likeability, inferences about causes of behavior, judgments about persons and actions, role-taking and cognitive tasks, and devaluation of forbidden toys.